Modern linear motion guide units in recent years are demanded to perform high-precious tasks on reciprocating parts for a variety of instruments including in various reciprocating parts or components including semiconductor manufacturing machines, assembling machines, medical instruments, inspection and/or measurement devices. Members and/or parts for the linear motion guide units are required to make as integral as possible to decrease any errors and steps in assembly. Moreover, slider is desired to free of any working such as small holes, threaded holes and so on. The linear motion guide units may be indispensable machine elements for machines to guide linearly the slider with nimbleness.
There has been already known a linear motion guide system with a lubrication construction which may be supplied with lubricant from the exterior, which is disclosed in, for example Japanese Laid-Open Patent Application No. H08-200 363. With the linear motion guide system constructed as stated earlier, a guide rail has on an inside surface thereof a groove allowing a load ball to roll through there and a slider has on an outside thereof a groove allowing a load ball to roll through there. The slider fits loosely in the guide rail to provide a circuit having non-load ball circuit in the slider. Thus, more than one ball is allowed to roll through load-ball rolling grooves in the non-load ball circulating circuits to move slider in an axial direction of the guide rail. With the linear guide system constructed as stated earlier, a lubricant injection port is made to communicate with the non-load ball circulating circuits. With the linear guide system constructed as stated earlier, the circulating circuits have the lubricant injection ports to communicate with the non-load ball circuit. The bottom plate of the guide rail has a lubricant port, which is allowed to communicate with the lubricant injection port after the slider has reached the preselected location in the guide rail.
In Japanese co-pending Published Patent Application No. S62-38 562, there is disclosed a linear motion roll-bearing composed of a bed of U-shaped configuration in cross-section of thin steel sheet and a table which fits in the bed for relatively linear movement with respect to the bed. With the prior linear motion roll-bearing constructed as stated earlier, the table fits over the circulator which has a looped circuit to allow the rolling elements to move along the raceway grooves in an endless manner. The table or the bed has no raceway groove at their lengthwise opposite ends thereof. Instead, there are provided lugs having fastening means to connect with any other members.
In another Japanese co-pending Laid-open Patent Application No. 2006-9 841, there is disclosed a linear motion guide unit in which the slider moving in a sliding manner along the track rail is composed of three members apart from the rolling members. The three members are fastened together to the carriage with no use of screws and so on to make it possible to accomplish extreme miniaturization. With the linear motion guide unit constructed as stated earlier, the slider moving in the gutter-shaped track rail is composed of a carriage having a load-carrying track groove and a non-loaded return groove, an upper lid to fit into the upper groove and a bottom lid to fit into lower groove in the carriage. The upper lid and the lower lid are fastened each other by means of pins extending through pin holes so as to grasp the carriage between the opposed lids.
With the linear motion roll-bearing constructed as stated earlier, however, as the circulator having the return passage and the turnaround passages of endless circuits is fastened with rivets in the table of thin steal sheet made U-shape in cross section, it has been required to set the combined circulators to the table and then squeeze rivets with using any press. This assembling procedure has had troublesome procedure. Moreover, because the prior linear motion roll-bearing leaves any clearance between, for example any locating holes in the carriage and the locating pins of the circulator, any rattling caused among parts leads to any discrepancy between parts, especially any misalignment in location between the scooping part of the circulator and the raceway groove of the carriage. As a result, the rolling elements are prevented from the smooth relative reciprocating movement and, therefore, the slider is hindered from smooth reciprocating movement relatively to guide rail.